Continuing calibration verification standards

A continuing calibration verification standard at a concentration that is close to the midrange of the calibration curve may be prepared either from the same stock solution as the initial calibration standard or from a standard of a different source. This CCV standard is analyzed at a certain frequency throughout sample analysis. 

Curves used in Conjunction with Continuing Calibration Verification Standards ... 

The sensitivity and other parameters of a quantitative method can change with time. Such changes can be sudden (as a result of, e.g., an electrical surge or a switch to a new batch of solvent) or gradual (reflecting, e.g., a drift in room temperature or deterioration of a column or accumulation of crud in an atmospheric pressure ionization (API) interface. Section 5.3.3). A continuing calibration verification standard (CCVS) consists of either a QC sample (an aliquot of control matrix spiked with a known amount of analytical standard if the calibration... 

An initial calibration verification standard should be measured after calibration and before measuring any sample. A calibration verification standard is a standard solution or set of solutions used to check calibration standard levels. The concentration of the analyte should be near either the regulatory level of concern or approximately at the midpoint of the calibration range. These standards must be independent of the calibration solutions and be prepared from a stock solution with a different manufacturer or manufacturer lot identification than the calibration standards. An acceptance criterion is set, usually as a maximum allowable percentage variation (e.g., 5%, 10%). The calibration can be continually verified using either a calibration standard or the initial calibration verification standard. Acceptance criteria must be set and action taken when results fall outside the limits (i.e., stop the analysis, investigate, correct the problem and rerun samples run between the verification standards that were not limits). 

Initial calibration Initial calibration verification with a second source standard Continuing calibration verification... 

Initial and continuing calibration verifications and acceptance limits Raw data for each sample (including reanalysis and second column confirmation), blanks, LCS/LCSD, MS/MSD, and calibration standards Sample preparation bench sheets Gel permeation chromatography clean-up logs / (Summary only) ... 

Method 200.8 specifies a variety of quality control standards. The first of these are the ICV and ICB (initial calibration verification and blank, respectively) samples. These must be run immediately after calibration and must be prepared from an alternative source to the calibration solutions. This test is designed to check the accuracy of the calibration. The CCV and CCB (continuing calibration verification and blank, respectively) samples are a similar check... 

After installation and qualification the instrument requires regular maintenance and calibration. The instrument should be maintained on a preventive maintenance plan and calibrated periodically according to a documented schedule. The schedule for preventive maintenance and performance verification/recalibration will depend on the instrument, its environment, and its function. The proposed U.S.P. chapter on NIR spectrophotometry [6] suggests that The purpose of instrument qualification is to assure that an instrument is suitable for its intended application and, when requalified periodically, it continues to function properly over extended time periods. Performance verification includes a validation based on a quality of fit to an initial scan or group of scans included in the instrument qualification.. . . With such testing, it is expected that reference standard spectra collected on a new or newly repaired, properly operating instrument should be identical to spectra of those standards collected over... 

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